1. Technical Field
This application relates to communication systems and, more particularly, to a self-contained data transfer channel.
2. Related Art
Cellular communication systems, such as the Global System for Mobile Communication (GSM), Universal Mobile Telecommunication System (UMTS), 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE), and LTE-Advanced (LTE-A), provide a means of exchanging information between a mobile device and another node or device over a wireless mobile data network. The information exchanged may include voice service, data relevant to a user application residing on the mobile device, or control information relevant to the “housekeeping” (e.g., information exchanged on control channels for radio resource control) of the mobile device or the network to which it is connected.
Except for cases of circuit-switched voice service, the information exchanged is packet-based, which means that the resources for transmission and reception of user data are allocated dynamically over time. To facilitate this relatively on-demand asynchronous exchange of information, signaling protocols have been developed which enable a mobile terminal to connect to a wireless network, transfer information, and then disconnect from the wireless network. These sequences typically incorporate the concepts of a) network access, b) packet data transfer setup, c) packet data transfer, and d) release of resources, or packet session tear-down. This is traditionally referred to as the call oriented approach to data transfer.
Many applications produce fairly frequent, but small amounts of data traffic on the wireless network. Such small data transmissions, when triggered by large numbers of user equipment (UE) devices, may occur frequently enough to create a congestion condition on the control plane of a wireless network. Machine type communication (MTC) is one example of a situation where frequent small amounts of data traffic are generated. With the proliferation of MTC, the frequency of small data packet transmissions is increasing exponentially and hence the total amount of signaling in the network compared to data may be disproportionally high. Further, the small amounts of data traffic may emanate from UEs that are synchronized as well as from those that are not synchronized, in which case they will need to use random access procedures which may further cause congestion on the random access channel (RACH).
In some systems, the network moves the UE in and out of connected mode after each data burst. In these systems, the signaling sequence that is required to access the wireless network may result in extremely high signaling overhead (compared to the actual amount of data exchanged). In addition to resulting excessive signaling, these extra signaling messages also consume UE battery power disproportionately. One option to reduce connection establishment signaling is to hold the UE in long term connected mode. The current design of mobile communication systems to achieve high data rates and spectral efficiencies impose higher cost as well as result in higher power consumption in the device in connected mode due to the need to support more complex operations on both the control plane as well as the user plane. For example, in LTE systems, decoding the current physical downlink control channel (PDCCH) alone requires the devices to perform a search for their Downlink Control Information (DCI) amongst a large set of possibilities (e.g., 64 for 10 MHz) and the devices are expected to monitor the control channels while in connected mode. This procedure increases the complexity, cost, and power consumption at the UE.